/*
 * p2d_contains_point.c - Determine whether polygon contains point/polygon
 *
 * Based on the algorithm by W. Randolph Franklin
 * http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
 * which is distributed under the following license, similar to the 3-clause
 * BSD license:
 *
 * Copyright (c) 1970-2003, Wm. Randolph Franklin
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimers.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice in the documentation and/or other materials provided with the
 *    distribution.
 * 3. The name of W. Randolph Franklin may not be used to endorse or promote
 *    products derived from this Software without specific prior written
 *    permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */


#include "poly2d.h"


int p2d_contains_point(const struct p2d *p, const struct v2d *v)
{
	const struct v2d *j, *i;
	int in = 0;

	j = p->v;
	do {
		i = j->next;
		if (((i->y > v->y) != (j->y > v->y)) &&
		    (v->x < (j->x-i->x)*(v->y-i->y)/
		    (j->y-i->y)+i->x))
			in = !in;
		j = i;
	}
	while (j != p->v);
	return in;
}